I want to board over my loft for storage, but before I do I ought to improve the insulation which is very old and thin. My UK house is 105yrs old so the rafters are not as high as the recommended thickness of fibreglass insulation.

Adding chipboard direct to the rafters will compress the insulation and reduce it's effectiveness. Do I really have to faff around with yet more bits of wood to raise the boards up further?

How much heat is lost through a double layer of cardboard boxes full of junk, anyway?!

...except they don't anymore. They've been gone from the B&Q website for a couple of months now, after being sold out for a long time. I haven't found anywhere else that sells them.
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Andy EJun 1 '12 at 8:36

yup, I contacted them about a month ago with no response. Thanks for digging that up for me, I looked around myself but couldn't find anything else. It's just a shame they're so expensive ― £14.95 per 10 adds a lot of wonga to the overall cost of boarding. Would you recommend these over screwing additional wood to the top of the joists to raise the height?
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Andy EJun 1 '12 at 10:35

1

@AndyE - That's a shame, it's always disappointing when you can't get hold of a product that would suit your purpose. I think if I were doing this, I would be inclined to make up stilts from lengths of 70x90mm timber, but it depends on whether time or money is more valuable to you. *8')
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Mark BoothJun 1 '12 at 10:51

One way to raise the floor is to run an additional set up of joists perpendicular to the existing trusses / joists / rafters. Then you can either blow in loose insulation or run an unfaced rolls of insulation between the new joists.

Make sure the attic floor is designed for the additional load. Some attics are not and you won't know of the issue until the next major snow storm when the the ceiling+roof collapses from the load.
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BMitch♦Dec 22 '11 at 22:33